Neverwinter Nights VS Neverwinter Nights 2

Fyrewind suggested last Sunday that I take a look at Neverwinter Nights, a game where I could create a campaign based on the Soulhers adventure. I’ve since downloaded the demo and am very interested at what this game can allow me to do. The only issue I have is, do I get the first game or its sequel?

The sequel has better graphics and uses the 3.5 rules set, but my understanding is that there are still many people playing the original game. So, which is best? and Why?